CAREER: Atomic-Scale Optical Microscopy of Ferroelectric, Quantum Paraelectric and Ferromagnetic Films

9701725 Levy这个职业项目旨在开发高分辨率的空间和时间分辨近场光学技术，以研究两种材料系统中的纳米尺度现象：（1）铁电体，量子顺电体，和（2）磁性薄膜。这项研究的主要目的是在短的长度和时间尺度上探索动力学过程，并将这些观测与宏观性质联系起来。对于铁电薄膜，畴反转和畴壁动力学将在MHz-THz频率下频闪成像，目的是了解微波耗散和介电色散的基本机制。脉冲产生的相干声子，畴壁，带电杂质和晶界之间的非线性相互作用将与预期的近原子的空间分辨率和时间分辨率低于声子周期进行研究。时间分辨技术将被用来探测有序无序铁电体中的序参数涨落，并在低温下寻找量子顺电体中宏观相干基态的特征。对于磁性薄膜，一个新提出的克尔效应近场显微镜将被开发的目的，研究磁化动力学的基本长度尺度和时间尺度。在耦合铁磁层的双二次交换的性质，和动态与热力学波动的作用，在重取向相变的磁性外延层也将得到解决。该项目解决了材料科学的前沿研究问题。 这项研究将在基本原子水平上为铁电和磁性材料的重要方面提供基本的材料科学知识。 该计划的一个重要特点是特别强调教育，并通过在基础和技术上重要的研究领域培养学生，将研究与教育相结合。 ***

9701725 Levy This CAREER project aims to develop high resolution spatially and temporally resolved near-field optical techniques to investigate nanometer-scale phenomena in two materials systems: (1) ferroelectrics, quantum paraelectrics, and (2) ultrathin magnetic films. The broad aim of this research is to probe dynamical processes at the short length and time scales, and to relate these observations to macroscopic properties. For ferroelectric thin films, domain reversal and domain wall dynamics will be imaged stroboscopically at MHz-THz frequencies, with the goal of understanding fundamental mechanisms for microwave dissipation and dielectric dispersion. Nonlinear interactions between impulsively generated coherent phonons, domain walls, charged impurities and grain boundaries will be studied with anticipated near-atomic spatial resolution, and time resolution below the phonon period. Time-resolved techniques will be used to probe order parameter fluctuations in order-disorder ferroelectrics, and to search for signatures of a macroscopically coherent ground state in quantum paraelectrics at low temperatures. For magnetic films, a newly proposed Kerr-effect near-field microscopy will be developed for the purpose of studying magnetization dynamics on fundamental length scales and time scales. The nature of biquadratic exchange in coupled ferromagnetic layers, and the role of dynamic versus thermodynamic fluctuations at the reorientation phase transition of ultrathin magnetic epilayers will also be addressed. %%% The project addresses forefront research issues in materials science. The research will contribute basic materials science knowledge at a fundamental atomic level to important aspects of ferroelectric and magnetic materials, in general. An important feature of the program is a special emphasis on education, and on the integration of research and education through the training of students in a fundamentally and technologically significant research area. ***